Document reading device

ABSTRACT

A document reading device ( 20 ) includes a document reading unit ( 5 ) that optically reads an image of a source document, a character string recognizer ( 102 ) that recognizes a character string included in a designated region in the source image read by the document reading unit ( 5 ), and an image storage controller ( 103 ) that stores the source image read by the document reading unit ( 5 ) in a storage device. The image storage controller ( 103 ) generates, when a character string recognized by the character string recognizer ( 102 ) in the source image in a designated page of the source document, and a character string recognized by the character string recognizer ( 102 ) in the source image in a preceding page are different from each other, one file including the source images up to the preceding page, and stores the file in the storage device ( 92 ).

TECHNICAL FIELD

The present invention relates to a document reading device thatelectronizes a document on a paper medium.

BACKGROUND ART

In the case of scanning a source document including a large number ofpages with a multifunction peripheral to generating a file of thedocument, the document may be divided into a plurality of files so as toreduce the file size, when the file size is excessively large. When theunit for dividing is specified by the file size or a certain number ofpages in such a case, the source document may be divided at a pageinconvenient to the user, depending on the type of the source document.In addition, it is very troublesome for the user to manually designatethe page at which the source document is to be divided. Accordingly, atechnique to automatically designate the page, at which the sourcedocument is to be divided, is being sought for.

A Patent Literature (PTL) 1 cited below discloses a technique,applicable to an image forming apparatus configured to read a sourcedocument composed of a plurality of pages and generate an electronicdocument, including extracting, according to a condition given by theuser, a prospective line where a chapter is to be divided, fromcharacter strings each constituting a line, extracted by characterrecognition from the source image read by the image forming apparatus,tentatively highlighting the image of the prospective line with amarker, displaying the image of the page including the prospective linetentatively highlighted with the marker, determining that theprospective line is established as the chapter dividing position,according to an instruction from the user, revising the source image byhighlighting the established chapter dividing position with a marker,generating outline data including link information, in which thecharacter string extracted from the line corresponding to the chapterdividing position and the chapter dividing position are associated witheach other, and generating the electronic document accompanied with thelink information, on the basis of the entirety of the source image andthe outline data.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No.2010-109420.

SUMMARY OF INVENTION

In PTL 1 cited above, for example the character size is utilized as oneof chapter dividing criteria. However, the criteria based on a rule,such as the character size, is only effective with respect to a sourcedocument made out in consideration of the rule, from the beginning.

The present invention has been accomplished in view of the foregoingsituation, and provides a technique to divide, when scanning a sourcedocument including a plurality of pages and generating files, the sourcedocument into a plurality of files at a page assumed to be convenient toa user, without the need for the user to designate the dividing page,and store the divided files.

SOLUTION TO PROBLEM

In an aspect, the present invention provides a document reading deviceincluding a document reading unit that optically reads an image of asource document, a designation reception unit that receives designationof a region in an optionally selected position in the source image,acquired through reading by the document reading unit, a characterstring recognizer that recognizes a character string included in theregion, the designation of which has been received by the designationreception unit, in the source image acquired through reading by thedocument reading unit, a storage device used to store the source imageread by the document reading unit, and an image storage controller thatstores the source image read by the document reading unit in the storagedevice. The image storage controller performs a file dividing operationincluding generating, when a character string recognized by thecharacter string recognizer in the source image of a preceding page ofthe source document, and a character string recognized by the characterstring recognizer in the source image of a current page are differentfrom each other, one file including the source images up to thepreceding page, and a separate file including the current and subsequentpages, and storing the file and the separate file in the storage device.

ADVANTAGEOUS EFFECTS OF INVENTION

The foregoing configuration enables, when scanning a source documentincluding a plurality of pages and generating a file, the sourcedocument to be divided into a plurality of files at a page assumed to beconvenient to the user, without the need for the user to designate thedividing page, and be stored in the divided state.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front cross-sectional view showing a configuration of animage forming apparatus including a document reading device according toan embodiment of the present invention.

FIG. 2 is a functional block diagram showing an essential internalconfiguration of the image forming apparatus.

FIG. 3A is a schematic drawing showing a setting example of a regiondesignated for character string recognition.

FIG. 3B is a schematic drawing showing another setting example of theregion designated for character string recognition.

FIG. 4 is a flowchart showing a file dividing operation performed by theimage forming apparatus.

FIG. 5 is a schematic drawing showing an example of a process of savingscanned source images divided into page groups, in separate files.

FIG. 6 is a schematic drawing showing an example of a process of savingthe source images in separate files, after correcting the orientation ofa source image turned upside down and dividing the source images intopage groups.

FIG. 7 is a schematic drawing showing an example of a process of savinga page in which a designated region is blank, in a separate file fromthat of the preceding page.

FIG. 8 is a schematic drawing showing an example of a process of savinga page in which the designated region is blank, in the same file as thatof the preceding page.

DESCRIPTION OF EMBODIMENTS

Hereafter, a document reading device according to an embodiment of thepresent invention will be described, with reference to the drawings.FIG. 1 is a front cross-sectional view showing a configuration of animage forming apparatus including the document reading device accordingto the embodiment of the present invention. The image forming apparatus1 is a multifunction peripheral configured to execute a plurality offunctions including, for example, a copying function, a printingfunction, a scanning function, and a facsimile function.

The image forming apparatus 1 basically includes a main body 11, adocument reading device 20 opposed to the main body 11 from an upperside, and an intermediate unit 30 interposed between the documentreading device 20 and the main body 11.

The document reading device 20 is mounted on the upper end portion ofthe intermediate unit 30. The document reading device 20 includes adocument reading unit 5, a document transport unit 6, and so forth.

The document reading unit 5 includes a contact glass 161 for placing asource document thereon, fitted in the upper opening of the casing ofthe document reading unit. The contact glass 161 includes a fixeddocument reading section (not shown) for reading a source documentplaced thereon, and a transported document reading section (not shown)for reading a source document being transported by the documenttransport unit 6. The document reading unit 5 further includes anopenable document holding cover 162 for holding the source documentplaced on the contact glass 161, and a reading device 163 that reads theimage of the source document placed on the fixed document readingsection of the contact glass 161, and also the image of the sourcedocument transported to the transported document reading section of thecontact glass 161. The reading device 163 optically reads the image ofthe source document with an image sensor such as a charge coupled device(CCD) or a complementary metal oxide semiconductor (CMOS), and generatesimage data.

The document transport unit 6 includes a document table 61 for placingone or more source documents thereon, a document discharge section 66 towhich the source document that has undergone the image reading isdischarged, and a document transport mechanism 65. The documenttransport mechanism 65 includes a feed roller, a transport roller, and adocument reversing mechanism, which are not shown. The documenttransport mechanism 65 picks up the source documents placed on thedocument table 61 one by one, by driving the feed roller and thetransport roller, to transport the source documents to the transporteddocument reading section of the contact glass 161, so that the readingdevice 163 reads the source documents. Then the document transportmechanism 65 discharges the source documents to the document dischargesection 66. The document transport mechanism 65 also causes the documentreversing mechanism to turn the source document face side down and againdeliver the source document to the transported document reading sectionof the contact glass 161, to allow the reading device 163 to read theimages on both sides of the source document.

Further, the document transport unit 6 is pivotably mounted on thedocument reading unit 5, so as to allow the front side of the documenttransport unit 6 to be lifted upward. When the upper face of the contactglass 161, serving as a table for the source document, is exposed bylifting up the front side of the document transport unit 6, the user canplace a source document to be read, for example a book opened so as toshow the left and right pages, on the contact glass 161.

An operation unit 47 is provided on the front side of the documentreading device 20. The operation unit 47 is used to input user'sinstructions related to the functions and operations that the imageforming apparatus 1 is configured to execute, for example an imageforming instruction and a source document reading instruction. Theoperation unit 47 includes a display unit 473 for displaying, forexample, an operation guide for the user.

The main body 11 includes an image forming unit 12, a fixing unit 13, apaper feed unit 14, and a sheet discharge section 15.

When the image forming apparatus 1 reads a source document, the documentreading unit 5 optically reads the image of the source document,transported by the document transport unit 6 or placed on the contactglass 161, and generates the corresponding image data. The image datagenerated by the document reading unit 5 is stored in a built-in HDD ora computer connected to a network.

When the image forming apparatus 1 forms an image, the image formingunit 12 forms a toner image on a recording sheet P, an example of arecording medium, supplied from the paper feed unit 14, on the basis ofthe image data generated by the source document, received from a userterminal such as a computer connected to a network or a smartphone, orstored in the built-in HDD. The image forming unit 12 includes imageforming subunits 12M, 12C, 12Y, and 12B, each of which includes aphotoconductor drum, a developing device that supplies the toner to thephotoconductor drum, a toner cartridge for storing the toner, a chargingdevice, an exposure device, and a primary transfer roller 126.

Toner images of the respective colors to be transferred onto anintermediate transfer belt 125 are superposed at an adjusted timing, soas to form a colored toner image. A secondary transfer roller 210transfers the colored toner image formed on the surface of theintermediate transfer belt 125 onto the recording sheet P transportedalong a transport route 190 from the paper feed unit 14 by a transportroller pair, at a nip region N of a drive roller 125A engaged with theintermediate transfer belt 125. Then the fixing unit 13 fixes the tonerimage onto the recording sheet P by thermal compression. The recordingsheet P having the colored image formed and fixed thereon is dischargedto an output tray 151.

A configuration of the image forming apparatus 1 will be describedhereunder. FIG. 2 is a functional block diagram showing an essentialinternal configuration of the image forming apparatus 1.

The document reading unit 5, controlled by the control unit 10, includesthe reading device 163 having a light emitter and a CCD sensor. Thedocument reading unit 5 is configured to read an image from the sourcedocument, by irradiating the source document with the light emitter andreceiving the reflected light with the CCD sensor.

An image memory 32 is a region for temporarily storing the documentimage data acquired through reading by the document reading unit 5, anddata to be printed by the image forming unit 12.

An image processing unit 31 retrieves the image read by the documentreading unit 5 from the image memory 32, and processes the image. Forexample, the image processing unit 31 executes predetermined imageprocessings such as shading correction, to improve the quality of theimage formed by the image forming unit 12 on the basis of the image readby the document reading unit 5.

The image forming unit 12 forms images, according to print data read bythe document reading unit 5, or print data received from a computerconnected to a network.

The operation unit 47 receives user's instructions related to thefunctions and operations that the image forming apparatus 1 isconfigured to execute. The operation unit 47 includes the display unit473, constituted of liquid crystal as a touch panel. The operation unit47 receives, for example, user's designation of a region in a desiredposition in the source image acquired through reading by the documentreading unit 5. The operation unit 47 exemplifies the designationreception unit in the present invention.

The display unit 473 displays an operation screen, a preview screen, aconfirmation screen of a print job status, and so forth, when the imageforming apparatus 1 is in a normal operation mode. When the imageforming apparatus 1 is in a sleep mode, the display unit 473 is turnedoff

A hard disk drive (HDD) 92 is a large-capacity storage device forstoring the source images read by the document reading unit 5.

A drive motor 70 serves as a drive source for supplying a rotationalforce to the rotary components of the image forming unit 12, and thetransport roller pair.

The control unit 10 includes a processor, a RAM, a ROM, an exclusivehardware circuit, and so forth. The processor is, for example, a CPU, aMPU, an ASIC, or the like. The control unit 10 includes a controller100, a character string recognizer 102, and an image storage controller103. Here, the HDD 92 or the ROM may contain a document reading program,and the control unit 10 may act as the controller 100, the characterstring recognizer 102, and the image storage controller 103, byoperating according to the document reading program, to execute theoperations necessary for executing the document reading described inthis embodiment. Alternatively, the control unit 10 may include thecontroller 100, the character string recognizer 102, and the imagestorage controller 103 in the form of a hardware circuit, instead ofoperating according to the document reading program.

The controller 100, which serves to control the overall operation of theimage forming apparatus 1, is connected to the document reading unit 5,the document transport unit 6, the image memory 32, the image processingunit 31, the image forming unit 12, the operation unit 47, and the HDD92, and controls the operation of the mentioned components.

The character string recognizer 102 recognizes a character stringincluded in a region designated in the source image read by the documentreading unit 5. To be more detailed, the character string recognizer 102utilizes an optical character recognition (OCR) technique, to recognizethe character string included in the designated region in the sourceimage.

FIG. 3A is a schematic drawing showing a setting example of a regiondesignated for character string recognition. For example, when thesource document is of a type “one-sided source document”, a chapternumber or caption may be provided in the header of each page.Accordingly, the user specifies a region designated for character stringrecognition 110, by designating the XY-coordinate of the start point andthe end point of the region in the header of the page, where the chapternumber or caption is provided, by manipulating the operation unit 47(e.g., slide operation on the touch panel) to input the designation.

FIG. 3B is a schematic drawing showing another setting example of theregion designated for character string recognition. For example, whenthe source document is of a type “spread source document”, the chapternumber or caption may be provided in the header of each of anodd-numbered page and an even-numbered page, at vertically symmetricalpositions. Accordingly, the user specifies a region designated forcharacter string recognition 110A, by designating the XY-coordinate ofthe start point and the end point of the region in the header of theodd-numbered page, where the chapter number or caption is provided, bymanipulating the operation unit 47, and specifies a region designatedfor character string recognition 110B in the even-numbered page, at theposition vertically symmetrical to the region in the odd-numbered page.

Further, when the character string recognizer 102 recognizes that thedesignated region in the source image is blank, the character stringrecognizer 102 recognizes a character string included in the designatedregion, in the image of the source image rotated by 180 degrees.Accordingly, in the case where a page turned upside down is mixed in thesource document, the orientation of the source image can be corrected,without the need for the user to correct the orientation of the page,which leads to improved user-friendliness. Here, whether the sourceimage is to be rotated by 180 degrees can be selected by the user asdesired.

The image storage controller 103 divides the source image read by thedocument reading unit 5 into a plurality of files, and stores the filesin the storage device such as the HDD 92, or a non-illustrated memory ofthe computer connected to the network. In particular, the image storagecontroller 103 performs a file dividing operation including generating,when a character string recognized by the character string recognizer102 in the source image of a preceding page of the source document, anda character string recognized by the character string recognizer 102 inthe source image of the current page are different from each other, onefile including the source images up to the preceding page, and storesthe generated file in the storage device. The image storage controller103 further generates a separate file including the current andsubsequent pages, and stores the separate file in the storage device.Here, the image storage controller 103 generates a file name of thesource image, on the basis of the character string recognized by thecharacter string recognizer 102. Therefore, the user can be exemptedfrom taking the trouble to manually input the file name, which leads toimproved user-friendliness.

Hereunder, a file dividing operation performed by the image formingapparatus 1 will be described. FIG. 4 is a flowchart showing the filedividing operation performed by the image forming apparatus.

First, the document reading unit 5 scans the source documents,transported one by one from the document transport unit 6, to opticallyread the image of the source documents (S1). The source image read bythe document reading unit 5 is temporarily stored in the image memory32.

When the scanning of one page of the source document is finished, thefile dividing operation is started, and the character string recognizer102 retrieves the source image temporarily stored in the image memory32, and recognizes the character string included in the designatedregion (S2).

In the case where the character string recognizer 102 is unable torecognize a character string in the designated region in the sourceimage, in other words the character string recognizer 102 has decidedthat the designated region is blank (YES at S3), it is probable that thepage is turned upside down. Accordingly, in the case where it ispermitted by the user to rotate the source image by 180 degrees (YES atS4), the character string recognizer 102 rotates the source image by 180degrees (S5), and recognizes the character string included in thedesignated region in the rotated image (S6).

In the case where the character string recognizer 102 has successfullyrecognized the character string, in other words the designated region isnot blank (NO at S3 or NO at S7), the image storage controller 103compares between the character string recognized by the character stringrecognizer 102 in the source image of the preceding page of the sourcedocument, and the character string recognized by the character stringrecognizer 102 in the source image of the current page (S8). In the caseof deciding that the character strings are different between thepreceding page and the current page (YES at S8), the image storagecontroller 103 generates one file including the source images up to thepreceding page, and stores the file in the storage device (S9). Thus,the files are divided between the preceding page and the current page,such that the file including the source images up to the preceding pageis stored in the storage device.

In the mentioned process, the image storage controller 103 does not, inprinciple, take the size or font of each of the character stringscompared with each other into account, when deciding whether thecharacter strings are different, but decides whether the characterstrings are different depending on whether the characters composing therespective character strings agree in terms of a text. However, theimage storage controller 103 may decide, with respect to the characterstrings compared with each other, whether the size or font of equal toor more than a predetermined number of characters in the characterstring (e.g., ½ of the total number of characters composing thecharacter string) is different between the character strings, and decidethat the character strings are different, when it is decided that thesize or font of equal to or more than the predetermined number ofcharacters is different between the character strings.

In the case where the image storage controller 103 decides that thecharacter strings of the preceding page and the current page are thesame (NO at S8), or that there is a next page of the source document,after the file including the source images up to the preceding page isstored at step S9 (YES at S10), the operation returns to step S1, wherethe document reading unit 5 reads the next page of the source document.In the case of deciding that there are no remaining pages of the sourcedocument (NO at S10), the image storage controller 103 generates onefile including unsaved source images, including that of the currentpage, and stores such file in the storage device (S11), thus finishingthe document reading operation.

FIG. 5 is a schematic drawing showing an example of a process of savingthe scanned source images divided into page groups, in separate files.For example, when a character string “4-19xxx” is provided in the headerof the first page and the second page of the source document, and acharacter string “4-20yyy” is provided in the header of the third pageand the fourth page, the source images of the first page and the secondpage of the source document are saved under a file name “4-19xxx.pdf”,and the source images of the third page and the fourth page are savedunder a file name “4-20yyy.pdf”, by the character string recognizer 102and the image storage controller 103, as result of the foregoingdocument reading operation.

FIG. 6 is a schematic drawing showing an example of a process of savingthe source images in separate files, after correcting the orientation ofa source image turned upside down and dividing the source images intopage groups. For example, when the third page is turned upside down inthe same source document as shown in FIG. 5, the character stringrecognizer 102 rotates the source image of the third page by 180 degreesto thereby recognize the character string “4-20yyy.pdf”. Then the imagestorage controller 103 saves the source images of the first page and thesecond page of the source document under the file name “4-19xxx.pdf”,and the source images of the third page and the fourth page under thefile name “4-20yyy.pdf”.

Now, the characters may not always be provided in the designated regionin all the pages of the source document and, for example, the chapternumber or caption may only be provided in the header of either of anodd-numbered page and an even-numbered page. In such a case, thedesignated region in the source image of the other page is without thecharacters, in other word blank. With respect to the source image ofsuch pages, the user may select, as desired, whether to regard the pagewith the blank as continuation from the preceding page and save the pagein the same file as the source image of the preceding page, or to savethe page with the blank in a separate file from the preceding page, andinput the selected instruction through the operation unit 47, so thatthe operation unit 47 receives such instruction. The image storagecontroller 103 determines the page at which the file is to be dividedaccording to the instruction, and generates each of the files.

Referring back to FIG. 4, in the case where the character stringrecognizer 102 has decided that the designated region is blank (YES atS3), and also where it is not allowed to rotate the source image by 180degrees (NO at S4), or in the case where the character string recognizer102 is unable to recognize a character string in the designated region,in other words the designated region is blank, despite rotating thesource image by 180 degrees (YES at S7), and also where the page inwhich the designated region is blank is not regarded as the continuationfrom the preceding page (NO at S12), the image storage controller 103saves the source images up to the preceding page in one file, and storessuch file in the storage device (S9). Thus, the current page in whichthe designated region is blank is separated from the preceding page, andthe file including the source images up to the preceding page is storedin the storage device.

FIG. 7 is a schematic drawing showing an example of a process of savinga page in which the designated region is blank, in a separate file fromthat of the preceding page. For example, when the designated region inthe third page of the source document is blank, the image storagecontroller 103 saves the source images up to the second page under thefile name “4-19xxx.pdf”. On the other hand, the source images of thethird and subsequent pages are saved by the image storage controller 103under the file name “4-20yyy.pdf”, on the basis of the character string“4-20yyy” recognized in the designated region in the source image of thefourth page.

In the case where the page in which the designated region is blank isregarded as the continuation from the preceding page (YES at S12), theimage storage controller 103 does not save the source images up to thepreceding page, and provided that there is a next page of the sourcedocument (YES at S10), the operation returns to step S1, where thedocument reading unit 5 reads the next page of the source document.

FIG. 8 is a schematic drawing showing an example of a process of savinga page in which the designated region is blank, in the same file as thatof the preceding page. For example, when the designated region in thethird page of the source document is blank, the third page is regardedas the continuation from the second page, and the image storagecontroller 103 stores the file named as “4-19xxx.pdf” including thesource images up to the third page, as well as the file named as“4-20yyy.pdf” including the source image of the fourth page, in thestorage device.

The configuration according to this embodiment enables, when scanning asource document including a plurality of pages to generate files, thesource document to be divided into a plurality of files at a pageassumed to be convenient to the user, without the need for the user todesignate the dividing page, and be stored in the divided state.Therefore, the user can be exempted from taking the trouble to manuallydesignate the page at which the source document is to be divided, whichleads to improved user-friendliness.

Here, the foregoing embodiment represents the case where the characterstring in the designated region is recognized and the file dividingoperation is performed, each time the scanning of one page of the sourcedocument is finished. In other words, the character string recognizer102 recognizes the character string in the designated region, and theimage storage controller 103 performs the file dividing operation, eachtime the document reading unit 5 has read one page of the sourcedocument. Instead, the character string in the designated region of eachof the pages may be recognized, and the file dividing operation may beperformed, after all the pages of the source document have been scannedand the source image data of all the pages is accumulated in the imagememory 32. In other words, the character string recognizer 102 mayrecognize the character string in the designated region in each of thepages, and the image storage controller 103 may perform the filedividing operation, after the document reading unit 5 have read all thepages of the source document, and accumulated the source image data ofall the pages in the image memory 32 (storage device).

Although some embodiments of the present invention have been describedas above, the present invention is not limited to the foregoingembodiments but may be modified in various manners. For example, theuser may designate the footer region or a region close to the verticaledge of the page, instead of the header region, as the region where thecharacter string is to be read, through the operation unit 47. In thiscase, naturally, the character string recognizer 102 recognizes thecharacter string in the region designated as above.

In the foregoing embodiment, further, the image storage controller 103may be configured to perform the file dividing operation specified in S2to S11, when a data amount of the source image read by the documentreading unit 5 at S1 above exceeds a predetermined data amount.

Although the foregoing embodiment represent the cases where the documentreading device according to the present invention is incorporated in themultifunction peripheral, the present invention is broadly applicable todifferent apparatuses, such as a copier, a facsimile machine, a scanner,and so forth.

The configurations and processings according to the embodiments,described with reference to FIG. 1 to FIG. 8, are merely exemplary andin no way intended to limit the present invention to thoseconfigurations and processings.

1. A document reading device comprising: a document reading unit thatoptically reads an image of a source document; a designation receptionunit that receives designation of a region in an optionally selectedposition in the source image, acquired through reading by the documentreading unit; a character string recognizer that recognizes a characterstring included in the region, the designation of which has beenreceived by the designation reception unit, in the source image acquiredthrough reading by the document reading unit; a storage device used tostore the source image read by the document reading unit; and an imagestorage controller that stores the source image read by the documentreading unit in the storage device, wherein the image storage controllerperforms a file dividing operation including generating, when acharacter string recognized by the character string recognizer in thesource image of a preceding page of the source document, and a characterstring recognized by the character string recognizer in the source imageof a current page are different from each other, one file including thesource images up to the preceding page, and a separate file includingthe current and subsequent pages, and storing the file and the separatefile in the storage device.
 2. The document reading device according toclaim 1, wherein the image storage controller performs the file dividingoperation, when a data amount of the source image read by the documentreading unit exceeds a predetermined data amount.
 3. The documentreading device according to claim 1, wherein the image storagecontroller generates a file name of the source image, on a basis of thecharacter string recognized by the character string recognizer.
 4. Thedocument reading device according to claim 1, wherein the characterstring recognizer recognizes the character string, by setting thedesignated region on each of an odd-numbered page and an even-numberedpage of the source document, at vertically symmetrical positions.
 5. Thedocument reading device according to claim 1, wherein the characterstring recognizer recognizes, upon recognizing that the designatedregion is blank, the character string included in the designated region,in an image formed by rotating the source image by 180 degrees.
 6. Thedocument reading device according to claim 1, wherein, when thecharacter string recognizer recognizes that the designated region in thesource image of the current page is blank, the image storage controllerperforms the file dividing operation including saving the source imageof the current page in one file, together with the source images up tothe preceding page, and saving one or more pages subsequent to thecurrent page in a separate file.
 7. The document reading deviceaccording to claim 1, wherein, when the character string recognizerrecognizes that the designated region in the source image of the currentpage is blank, the image storage controller performs the file dividingoperation including saving the source image of the current page in onefile, together with the source image of one or more pages subsequent tothe current page, and saving one or more pages preceding the currentpage in a separate file.
 8. The document reading device according toclaim 1, wherein the image storage controller performs the file dividingoperation on an assumption that the character string recognized by thecharacter string recognizer in the source image in the preceding page ofthe source document, and the character string recognized by thecharacter string recognizer in the source image in the current page aredifferent from each other, when the character string recognizer decidesthat the characters composing the respective character strings aredifferent in terms of a text, instead of deciding whether a size or fontof each of the character strings is different.
 9. The document readingdevice according to claim 1, wherein the image storage controllerperforms the file dividing operation on an assumption that the characterstring recognized by the character string recognizer in the source imagein the preceding page of the source document, and the character stringrecognized by the character string recognizer in the source image in thecurrent page are different from each other, when the character stringrecognizer decides that the size or font of equal to or more than apredetermined number of characters is different between the characterstrings.
 10. The document reading device according to claim 1, whereinthe character string recognizer recognizes the character string in thedesignated region, and the image storage controller performs the filedividing operation, each time the document reading unit has read onepage of the source document.
 11. The document reading device accordingto claim 1, wherein the character string recognizer recognizes thecharacter string in the designated region in each of pages, and theimage storage controller performs the file dividing operation, after thedocument reading unit have read all the pages of the source document,and accumulated the source image data of all the pages in the storagedevice.